Transmission bolt pattern

krivman65 · 11-14-2011, 12:26 AM

Hey all, I have a '73 RX-2 with an automatic transmission behind it. I found a running '84 12A with a 5spd for sale, and I was wondering if anyone knew if these were the same bolt pattern? Also, My car is a very nice original car, and the engine needs to be rebuilt because it is seized. Would it be worth grabbing this engine and tranny? He is asking $500 for both. I would probably sell the 5spd, as my car came with the automatic(even though the 5spd would be much more fun

Any and all opinions are appreciated!

Thanks,

--Chad

rxtasy3 · 11-15-2011, 01:40 PM

engine to tranny pattern is the same. u could probably use the flex plate off the 73 on the 84 but to keep balance u'll need the auto counter weight for the 84.

krivman65 · 11-15-2011, 10:06 PM

Awesome. Also, I have been told that the motor mounts are different??? I guess the later ones don't have a side mount?

charlie Rx3 · 11-24-2011, 10:11 PM

I think all the 12a have the motor mount in the front like the stock Rx2.The only 1 with the side mount are the 3rd gen Rx7.The only thing you need to use is your front stock eng mount cross bar.

85rx-7gsl-se · 11-24-2011, 11:51 PM

Any fb rx7 motor will have the front plate for front mounting.

kansei · 02-26-2012, 05:09 PM

Quote:

Originally Posted by rxtasy3

engine to tranny pattern is the same. u could probably use the flex plate off the 73 on the 84 but to keep balance u'll need the auto counter weight for the 84.

Be careful here- 1973 was a split year, twice over. I'm assuming you already know that if youhave an early '73 with the top mount starter, nothing will line up with an SA/FB engine rear iron. Even if you have the bottom mount starter on your RX-2, you may still have the early bottom mount starter rear iron, which still would not permit your trans to directly bolt to the SA/FB engine, as those still shared the earlier bolt pattern of the top mount starter engines. Only the very late 1973 cars with the single distributor engines (note I said very late '73) might directly bolt up to the 1st gen engine without trouble. If you have a typical 1973 model, you probably have a dual distributor engine, in which case you need to research the VIN splits to make sure everything will bolt up OK before tearing everything apart.

The engine mounts on the earlier RX-2s and RX-3s are different than the RX-7s, though you should be able to just swap the engine mount bar over from the RX-2 engine onto the RX-7 engine and continue running the RX-2 engine mounts. IIRC, the geometry of the RX-2 front subframe engine mount brackets will not permit the RX-7 engine mount bar and RX-7 engine mounts to be used without altering the angle the engine sits at, nor keep it level side to side. I know there is a way to make it work properly using a mix and match of different pieces, I just don't recall offhand what that combination is.

Neal.

mattallac · 02-27-2012, 01:50 AM

I would put the 5 speed in and get rid of the auto , the last post is exactly right in the split years . the FA manual will fit in the stock tunnel hole and the FB needs to be shortened 103mm .If the twin dizzy is stuck the first gen motor is a better fit .I have 2 73 rx2s and it can pose as a problem ,you need to play with the rx2 and rx7 motor mounts as they are different in the motor set back .Trans mounts are easy to make so that might be a must ,also check your pinion angle (stock) and see what the difference is with the rx7 stuff . you want the angles to match so you don't pre maturely wear your drive shaft bearings.A ll the rx2 to rx7 mods are a pain in the ass but the rx7 stuff is better for the horse power (more solid ) .Even the threads on the brake lines is different . Time and cation is the biggest part of the build .

Rotarydave · 02-27-2012, 10:22 AM

Quote:

Originally Posted by mattallac

I would put the 5 speed in and get rid of the auto , the last post is exactly right in the split years . the FA
(This should be SA) manual will fit in the stock tunnel hole and the FB needs to be shortened 103mm .If the twin dizzy is stuck the first gen motor is a better fit .I have 2 73 rx2s and it can pose as a problem ,you need to play with the rx2 and rx7 motor mounts as they are different in the motor set back .Trans mounts are easy to make so that might be a must ,also check your pinion angle (stock) and see what the difference is with the rx7 stuff . you want the angles to match so you don't pre maturely wear your drive shaft bearings.A ll the rx2 to rx7 mods are a pain in the ass but the rx7 stuff is better for the horse power (more solid ) .Even the threads on the brake lines is different . Time and cation is the biggest part of the build .

The tranny that he is talking about being a more direct fit is the 79-80 Rx7 one or any pre rx7 manual tranny from 74-78. both posters got their info right. You can change the bell housing on your automatic which will allow it(your tranny and the later engine) to work, it is just a little more effort, it would take the later flexplate and later starter. One thing not mentioned in any of this. You will have to modifiy the transmission tunnel to use a bottom mount starter. This modification is typically done with a sledge hammer because there is no inset for the starter to fit into. Also not mention but will need to be done is the oil pan from your engine must be swapped over to the rx7 one.

there are lots of little ankle biters that can get you on this swap but it has been done frequently with good results, just take you time and think it through

mattallac · 02-27-2012, 06:20 PM

I had the 79-80 FA trans in my repu ,the only problem is they are getting harder to find and they cant' handle to much HP. The FB trans are easy to shorten and easy to find ,and the starter is an issue ,no sledge hammer though .I use an air chisel with a planishing hammer attachment (you can find the hammer end at Eastwood on line)and a palm nailer with a carige bolt in it .Its fast and easy with clean results (does not look like you modified the tunnel when your done ).Good luck p.s. they're are so many little things to do it can be hard to get all the info .

surem · 02-28-2012, 10:27 AM

U can use a 81-85 12A tranny.... All u have to do is just need to shorten it. There a post on another forum that shows u in detail how shorten it about 4 inches to fit inside ur tranny tunnel with out cutting up ur car. If u look and read around there are many option u have.

krivman65 · 03-19-2012, 11:57 PM

Hey all, thanks for the responses! I finally got back out to working on the car a couple of days ago, and yes, the new transmission is different. I am going to re-use the original tranny(yes, I would like a 5spd, but I don't want to hack up this car) and keep my fingers crossed that it is still ok. I didn't realize that the front mount was different. Thanks for that information! I will switch it over. Now, I am worried about the wiring- I don't want to hack up the wiring but don't know what to do. One example is going from 2 distributors to one... Also, since I am not using the 5spd, I am selling it. It comes with a new clutch and a flywheel that could use to be turned. I am thinking 150 bucks for all of it... I don't know what it is worth but I don't need it.
Any and all input would be fantastic. Thanks guys!

--Chad

krivman65 · 03-19-2012, 11:58 PM

Oh, and yes, I noticed the oil pan thing as well. I swapped it the other night. Thank you again for the help!

11-14-2011, 12:26 AM	#1
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	Transmission bolt pattern Hey all, I have a '73 RX-2 with an automatic transmission behind it. I found a running '84 12A with a 5spd for sale, and I was wondering if anyone knew if these were the same bolt pattern? Also, My car is a very nice original car, and the engine needs to be rebuilt because it is seized. Would it be worth grabbing this engine and tranny? He is asking $500 for both. I would probably sell the 5spd, as my car came with the automatic(even though the 5spd would be much more fun Any and all opinions are appreciated! Thanks, --Chad

11-15-2011, 01:40 PM	#2
rxtasy3 rotary madness Join Date: Apr 2010 Location: spartanburg, sc iTrader: (0) Posts: 78 Rep Power: 15	engine to tranny pattern is the same. u could probably use the flex plate off the 73 on the 84 but to keep balance u'll need the auto counter weight for the 84.

11-15-2011, 10:06 PM	#3
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	Awesome. Also, I have been told that the motor mounts are different??? I guess the later ones don't have a side mount?

11-24-2011, 10:11 PM	#4
charlie Rx3 The Newbie Join Date: Jan 2009 iTrader: (0) Posts: 21 Rep Power: 0	I think all the 12a have the motor mount in the front like the stock Rx2.The only 1 with the side mount are the 3rd gen Rx7.The only thing you need to use is your front stock eng mount cross bar.

02-27-2012, 01:50 AM	#7
mattallac Rotary Fanatic Join Date: Aug 2011 Location: crockett ca. iTrader: (1) Posts: 176 Rep Power: 0	I would put the 5 speed in and get rid of the auto , the last post is exactly right in the split years . the FA manual will fit in the stock tunnel hole and the FB needs to be shortened 103mm .If the twin dizzy is stuck the first gen motor is a better fit .I have 2 73 rx2s and it can pose as a problem ,you need to play with the rx2 and rx7 motor mounts as they are different in the motor set back .Trans mounts are easy to make so that might be a must ,also check your pinion angle (stock) and see what the difference is with the rx7 stuff . you want the angles to match so you don't pre maturely wear your drive shaft bearings.A ll the rx2 to rx7 mods are a pain in the ass but the rx7 stuff is better for the horse power (more solid ) .Even the threads on the brake lines is different . Time and cation is the biggest part of the build .

02-27-2012, 06:20 PM	#9
mattallac Rotary Fanatic Join Date: Aug 2011 Location: crockett ca. iTrader: (1) Posts: 176 Rep Power: 0	I had the 79-80 FA trans in my repu ,the only problem is they are getting harder to find and they cant' handle to much HP. The FB trans are easy to shorten and easy to find ,and the starter is an issue ,no sledge hammer though .I use an air chisel with a planishing hammer attachment (you can find the hammer end at Eastwood on line)and a palm nailer with a carige bolt in it .Its fast and easy with clean results (does not look like you modified the tunnel when your done ).Good luck p.s. they're are so many little things to do it can be hard to get all the info .

02-28-2012, 10:27 AM	#10
surem Rotary Fan in Training Join Date: Nov 2010 iTrader: (0) Posts: 62 Rep Power: 15	U can use a 81-85 12A tranny.... All u have to do is just need to shorten it. There a post on another forum that shows u in detail how shorten it about 4 inches to fit inside ur tranny tunnel with out cutting up ur car. If u look and read around there are many option u have.

03-19-2012, 11:57 PM	#11
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	Hey all, thanks for the responses! I finally got back out to working on the car a couple of days ago, and yes, the new transmission is different. I am going to re-use the original tranny(yes, I would like a 5spd, but I don't want to hack up this car) and keep my fingers crossed that it is still ok. I didn't realize that the front mount was different. Thanks for that information! I will switch it over. Now, I am worried about the wiring- I don't want to hack up the wiring but don't know what to do. One example is going from 2 distributors to one... Also, since I am not using the 5spd, I am selling it. It comes with a new clutch and a flywheel that could use to be turned. I am thinking 150 bucks for all of it... I don't know what it is worth but I don't need it. Any and all input would be fantastic. Thanks guys! --Chad

03-19-2012, 11:58 PM	#12
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	Oh, and yes, I noticed the oil pan thing as well. I swapped it the other night. Thank you again for the help!